Netflix’s latest fantasy epic may just be their most impressive yet. A prequel to the 1982 cult classic Jim Henson film The Dark Crystal, The Dark Crystal: Age of Resistance is a marvel to behold. Age of Resistance is quite possibly the most ambitious puppet series ever attempted, with hundreds of practical sets and physical puppets created by master craftspeople in order to bring the realm of Thra to life. But while all of that hard work would still be dazzling to watch on TV, it wouldn’t cut as deep without story and character–and Dark Crystal has plenty of story and character. Nowhere is that more evident than in the journey of Seladon, a princess of the Vapra clan and the sister to two equally tenacious Gelflings (Tavra and Brea). But whereas Tavra is wise and Brea is curious, Seladon’s character arc unfolds in a completely different manner–and it makes for the most surprising character arc of the entire season. And here’s a spoiler warning if you haven’t hit the Season 1 halfway mark yet.

Halfway through the season, Seladon hits a wall. Whereas her sister Brea is fighting like mad to expose the cruelty and corruption in Skeksis rule, Seladon wants nothing more than to believe in them. She doesn’t want to let go of the very hierarchy that she’s lived in for her entire life. And when Seladon sees her mother the All-Maudra murdered by the Skeksis for attempting an insurrection, she goes full Dark Phoenix. Instead of seeing this as proof of Brea’s findings, she doubles down, disowns her mother for being a traitor, and undergoes a goth makeover to make her even more Skeksis-y.

Photo: Netflix

When Decider talked to Jeffrey Addiss and Will Matthews, the writing team that developed The Dark Crystal: Age of Resistance, we had to ask how they developed Seladon’s truly surprising storyarc. It turns out that the Gelfling’s slow descent into villainy took the writers by surprise, too.

“She was not first imagined to have such a big or complicated role,” explained Matthews. “I remember I was reading Joe [M. Lee]’s [Dark Crystal] books–we were weeks into the [writers’] room working on the series, and Seladon wasn’t in the show. I remember I was reading the latest book Joe was working on, it hadn’t come out yet, and I noticed that there was another sister and I just remember coming in and saying, ‘We just gotta remember to add in the name Seladon. She’s in there.’ It was really [director] Louis Leterrier who focused on this idea of, ‘Wait a minute, there’s a story here with the three sisters. There’s something worth pursuing here.’ And so we did, and we got into Seladon’s arc and one of the things we really wanted to do on the show was make sure that all of the bad guys were reasonable people with strong points of view that makes some sense. They’re not just villains, they’re not just twirling their mustaches. So whether it’s Seladon or the Chamberlain, they’re not wrong, they just might not agree with our heroes.”

Seladon really came alive in the hands of puppeteer Helena Smee and voice actor Gugu Mbatha-Raw. Together, they created a performance that conveyed a complex internal life, quite a feat considering Seladon is really a piece of meticulously crafted foam.

“She is a character that definitely surprised me in the writing and then in the performance,” said Matthews. “One of the things you worry about with puppets, because no one’s really done anything like this before, no one knew what the limits were. So we would write ‘Seladon cuts her eyes across the room’ and you’re like, ‘Can a puppet sell that, thinking and scheming and menacing?’ And then the puppeteer got in there and what she could do was unbelievable. And then when Gugu [Mbatha-Raw] started doing the voice, I mean, the character just came to life in such an unexpected and fantastic way.”

The Dark Crystal: Age of Resistance is currently streaming on Netflix.